Re: [PATCH v3 5/6] x86/microcode/intel: Support mailbox transfer

[Chao Gao <chao.gao@intel.com>]

>+/*
>+ * Wait for the hardware to complete a transaction.
>+ * Return true on success, false on failure.
>+ */
>+static bool wait_for_transaction(struct staging_state *ss)
>+{
>+	u32 timeout, status;
>+
>+	/* Allow time for hardware to complete the operation: */
>+	for (timeout = 0; timeout < MBOX_XACTION_TIMEOUT_MS; timeout++) {
>+		msleep(1);
>+
>+		status = readl(ss->mmio_base + MBOX_STATUS_OFFSET);
>+		/* Break out early if the hardware is ready: */
>+		if (status & MASK_MBOX_STATUS_READY)
>+			break;

Shouldn't we exit the loop if the MASK_MBOX_STATUS_ERROR is set, or is the
ERROR bit always set in conjunction with the READY bit?

>+	}
>+
>+	status = readl(ss->mmio_base + MBOX_STATUS_OFFSET);

I still think this read is not needed.

>+
>+	/* Check for explicit error response */
>+	if (status & MASK_MBOX_STATUS_ERROR) {
>+		ss->state = UCODE_ERROR;
>+		return false;
>+	}
>+
>+	/*
>+	 * Hardware is neither responded to the action nor
>+	 * signaled any error. Treat the case as timeout.
>+	 */
>+	if (!(status & MASK_MBOX_STATUS_READY)) {
>+		ss->state = UCODE_TIMEOUT;
>+		return false;
>+	}
>+
>+	ss->state = UCODE_OK;
>+	return true;
>+}